Roles of Pbp1, Mkt1, and Dhh1 in the regulation of gene expression in the medium containing non-fermentative carbon sources.

Pbp1, a yeast ortholog of human ataxin-2, is important for cell growth in the medium containing non-fermentable carbon sources. We had reported that Pbp1 regulates expression of genes related to glycogenesis via transcriptional regulation and genes related to mitochondrial function through mRNA stability control. To further analyze the role of Pbp1 in gene expression, we first examined the time course of gene expression after transfer from YPD medium containing glucose to YPGlyLac medium containing glycerol and lactate. At 12 h after transfer to YPGlyLac medium, the pbp1∆ mutant showed decreased expression of genes related to mitochondrial function but no decrease in expression of glycogenesis-related genes. We also examined a role of the Pbp1-binding factor, Mkt1. The mkt1∆ mutant, like the pbp1∆ mutant, showed slow growth on YPGlyLac plate and reduced expression of genes related to mitochondrial function. Furthermore, we found that mutation of DHH1 gene encoding a decapping activator exacerbated the growth of the pbp1∆ mutant on YPGlyLac plate. The dhh1∆ mutant showed reduced expression of genes related to mitochondrial function. These results indicate that Pbp1 and Mkt1 regulate the expression of genes related to mitochondrial function and that the decapping activator Dhh1 also regulates the expression of those genes.